1. Field of the Invention
This invention relates to a magnetic recording/playback apparatus for a rotating magnetic recording medium (hereinafter referred to as a magnetic disk) capable of advancing a magnetic head in a direction to contact the magnetic disk in order to write a signal on any desired track or read a recorded signal from any desired track, and of retracting the magnetic head in a direction away from the magnetic disk.
2. Description of the Background Art
Electronic still camera systems have recently been developed. These systems combine an imaging device such as a solid state imaging element or image pickup tube with a recorder that employs an inexpensive magnetic disk of comparatively large storage capacity as a storage medium. The systems operate by electronically imaging a subject, recording a still picture of the subject on the magnetic disk and reproducing the recorded picture by a separately provided television system or printer. A video magnetic recording system has also been realized in which a still picture recorded on a visible recording medium such as ordinary film or photographic paper is imaged and recorded on a magnetic disk.
In systems of this kind, a video signal is recorded on the magnetic disk or read from the magnetic disk not by merely contacting the magnetic recording/playback head with the recording surface of the disk lightly but by pressing the head against the disk surface so strongly that the disk is partially deformed. Since the magnetic disk has some flexibility and therefore returns to its original state even when somewhat deformed, no problems are encountered even though the magnetic head is pressed against the rotating magnetic disk during recording or playback. However, when rotation of the magnetic disk is halted and the magnetic head is held in abutting contact with one location on the stationary magnetic disk, the portion of the disk in contact with the magnetic head becomes permanently deformed and is scarred or left with an impression of the head if such contact is allowed to continue for an extended period of time (e.g. for several hours to several days).
In an effort to solve this problem, devices of various types have been proposed for loading and unloading the magnetic head, namely for moving the magnetic head in a direction orthogonal to the surface of the disk to bring the head into contact with the disk (loading), and for moving the head away from the disk (unloading). Many of these loading/unloading devices are designed to repeat the loading/unloading of the magnetic head quite frequently, namely whenever a signal is recorded on or played back from a magnetic disk, whenever rotation of the magnetic disk starts, or whenever the magnetic head is transferred from one track to the next. Consequently, it is required that the loading/unloading device have a great amount of durability. Another problem that results is the occurrence of malfunction as due to wear, which develops comparatively quickly.